The present invention relates to an internal combustion engine with a balancer shaft and a method of assembling the same.
An internal combustion engine with a pair of balancer shafts is disclosed in Japanese Patent Provisional Publication No. 6-33989. In the engine, a balancer housing is disposed under an engine block. A drive side balancer shaft and driven side drive balancer shaft having respective eccentric weight portions are disposed within the balancer housing so as to be parallel with a crankshaft and rotatable in timed relation with each other. Between the crankshaft and the drive side balancer shaft is disposed a power transmitting mechanism including a pair of sprockets and a chain for transmitting rotation of the crankshaft to the drive side balancer shaft.
Namely, one of the sprockets is installed on the end portion of the crankshaft and the other is installed on the end portion of the drive side balancer shaft. Then, the chain is wound around the sprockets and thereafter the tension of the chain is adjusted by a chain guide and a tensioner.